Organic semiconductor material

ABSTRACT

Compounds useful as organic semiconductor materials, and semiconductor devices containing such organic semiconductor materials are described.

The present invention relates to a novel ambipolar organic semiconductormaterial, and semiconductor devices containing said ambipolar organicsemiconductor material.

It is known that organic semiconductors are materials into which chargecan be reversibly introduced by the application of electromagneticenergy or chemical dopants. The electronic conductivity of thesematerials lies between that of metals and insulators, spanning a broadrange of 10⁻⁹ to 10³ Ω⁻¹ cm⁻¹. As in traditional inorganicsemiconductors, organic materials can function either as p-type orn-type. In p-type semiconductors the majority carriers are holes, whilein n-type the majority carriers are electrons.

The vast majority of the prior art has focused on the design, synthesis,and structure-property relationships of p-type organic semiconductormaterials, including: oligoacenes, fused oligothiophenes,anthradithiophenes, carbazoles, oligophenylenes, and oligofluorenes,some of which have resulted in field-effect transistors with performancesuperior to amorphous silicon. In contrast, the development of n-typeand ambipolar oligomer and polymer semiconductors has lagged behindp-type materials. In fact, compared to the p-type semiconductors, n-typeand ambipolar semiconductors are still not fully developed, and theperformances are not satisfactory. Materials with n-type and ambipolarcharge transport are highly desirable to realize complementaryintegrated circuits and integrated organic devices such as lightemitting transistors, leading to flexible, large-area, and low-costelectronic applications.

A variety of organic semiconductors have been considered in the art asn-type organic semiconductor materials.

Aromatic tetracarboxylic anhydride and their diimide derivatives werereported among the first n-channel materials. Among the materials ofthis class, perylenetetracarboxylic diimides having fluorinated sidechains showed mobilities up to 0.72 cm²V⁻¹s⁻¹, which only slightlydecreased upon air exposure. Air stability, packing grain size andmorphology of the deposited films as well as electrical performance canbe altered by varying side-chain length, insertion of oxygenated groupsand degree of fluorination. However, most of the perylene buildingblocks, due to the structural rigidity and moderate solubility, do notallow readily structural changes limiting the volume of materialsaccessible.

Other classes of n-type organic materials have been described such ascyanovinyl oligomers, fullerenes.

J. Am. Chem. Soc. 2009, 131, 16616-16617 describes ambipolar chargetransport properties of diketopyrrolopyrrole-copolymers.

A benzothiadiazole-diketopyrrolopyrrole copolymer described in Mater.2010, 22, 47, 5409-5413, shows high and balanced hole- and electronmobilities of 0.35 cm²V⁻¹s⁻¹ and 0.40 cm²V⁻¹s⁻¹, respectively. Largerelectron mobilities values up to 0.85 cm²V⁻¹s⁻¹ were achieved in air forelectron-only transporting n-type polymer, calledpoly{[N,N9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)},(Polyera Activink N2200), in a staggered top gate configuration.

N-type semiconductor materials consisting of oligothiophenes bearingfluorinated side groups have been also described in J. Am. Chem. Soc.2005, 127, 1348 and Angew. Chem. Int. Ed. 2003, 42, 3900. Theseoligomers showed mobilities up to 0.43 cm²V⁻¹s⁻¹. However, OFETs basedon most of these perfluoroaryl and perfluoroalkylaryl substitutedmaterials were unstable in air or suffered from high threshold voltage.Fluorocarbonyl-functionalized oligomers were also described, whichshowed improved air stability, but lower electron mobilities withrespect to fluorinated oligomers.

Oligomers and polymers containing a bithiophene-imide units as innercore have also been described.

For example, J. Am. Chem. Soc. 2008, 130, 9679-9694 describesN-alkyl-2,2′-bithiophene-3,3′-dicarboximide-based homopolymers andcopolymers showing p-type or n-type semiconductor behavior depending onthe polymeric structure. However, no air-stable devices could beachieved with such materials. In addition, the poor reactivity of thestarting dihalogenated bithiophene-imide compounds limits theaccessibility of this class of materials.

J. Am. Chem. Soc. 1998, 120, 5355-5362, Tetrahedron Letters 44(2003)1563-1565 disclose copolymers containing electron poor3,4-imido-thienyl blocks alternated to electron rich amino substitutedthienyl blocks. No investigation was performed regarding the electricalproperties of such copolymers.

N-alkylated poly(dioxopirrolothiophene)s are described in OrganicLetters 2004, 6, 19, 3381-3384. However, no proof of an efficient n-typebehavior in OFET devices is reported.

Each of the afore mentioned class of materials has poor electricalperformances.

WO2008/127029 relates to dioxypirrolo-heterocyclic compounds having thepyrrole moiety fused to the 3,4 position of the thienyl ring and organicelectronic devices using said dioxypirrolo-heterocyclic compounds.

Wei Hong et al, “Linear fused dithieno [2,3-b: 3′2′-d]thiophenediimides” Organic Letters, vol 13, no. 6, 18 Mar. 2011, pages 1420-1413,discloses a class of linear fully fused dithieno thiophene diimides.

The documents: DE1954550; Ronova Iga A et al: “The effect ofconformational rigidity on the initial decomposition temperature of someheterocyclic polyimides”, High Performance Polymers, Institute ofPhysics Publishing, Bristol G B, vol. 14, No. 2, 1 Jan. 2002, pages195-208; and Gaina C. et al, “Polyimides containing 1,4-dithiine unitsand their corresponding thiophene 2,3,4,5 tetracarboxylimide units” HighPerformance Polymers, Institute of physics publishing, Bristol G B, vol.11, No. 2, 1 Jun. 1999, pages 185-195, disclose polymeric diimmidecompounds in which the member connecting the polymer repeating units isthe N-imidic substituent. The three last cited documents do not mentionany semiconductor property of the compounds therein disclosed.

WO2006/094292 discloses thienopyridine compounds capable of modulatingthe stability and/or activity of hypoxia inducible factor,pharmaceutical compositions comprising said compounds and chemicalintermediates useful for preparing said compounds. Among said chemicalintermediates, specific compounds having a4,6-dioxo-thieno[2,3-c]pyrrole nucleus are disclosed.

EP0467206 discloses specific compounds having a4,6-dioxo-thieno[2,3-c]pyrrole nucleus and their use as herbicide.

However, WO2006/094292 and EP0467206 do not teach the semiconductorproperties of said compounds.

Therefore, there is still the need of n-type organic semiconductormaterials or compounds that possess higher electron mobility properties.

In the present specification and in the claims, the term “n-type organicsemiconductor” means a material that, inserted as active layer in afield effect device architecture with a source, a drain and gate controlelectrodes, shows an electron mobility higher than 10⁻⁷ cm²V⁻¹s⁻¹.

It is an object of the present invention to provide new organicmaterials suitable for use as semiconductor material which is free fromsaid disadvantages. Said object is achieved with compounds whose mainfeatures are disclosed in the first claim, a use of said compound whosemain features are disclosed in claim 10 and an electronic device whosemain features are disclosed in claim 13. Other features of said compoundare disclosed in claims 2 to 9.

Advantageously, the compounds according to the present invention may beuseful as p-type, n-type or ambipolar organic semiconductor material.

Particularly, the compounds according to the present invention possesshigh electron mobility properties, excellent stability under atmosphericconditions and arc accessible through synthetically easy processes.

In addition, most of the compounds according to the present inventionare provided with electroluminescence, in addition to the abovementioned ambipolar charge transport properties. This is of crucialinterest for the realization of advanced single layer ambipolar organiclight emitting transistors (OLET) with low manufacturing costs.

Further advantages and features of the compounds, materials and devicesaccording to the present invention will become clear to those skilled inthe art from the following detailed and non-limiting description of anaspect thereof with reference to the attached drawings, wherein:

FIGS. 1 (a) and (b) show absorption and emission spectra of a compound 6according to the present invention in CH₂Cl₂ solution and 30 nm thickvacuum sublimed film;

FIG. 2 shows a cyclic voltammetry of a preferred compound 6 according tothe present invention;

FIG. 3 (a) shows a X-ray diffraction analysis of a compound 6 accordingto the present invention on a SiO2 substrate;

FIG. 3 (b) shows a X-ray diffraction analysis of a compound 6 accordingto the present invention on a OFET device;

FIG. 4 shows an Atomic Force image of a 30 nm thick film of compound 6according to the present invention, grown on PMMA;

FIGS. 5 (a) and (b) show electrical characteristics for OTFTs comprisinga 30 nm thick film of compound 6;

FIG. 6 shows opto-electronic transfer curves of an OLET device;

FIGS. 7 (a) and (b) show absorption and emission spectra of a compound 8according to the present invention in CH₂Cl₂ solution and 30 nm thickvacuum sublimed film;

FIG. 8 shows a cyclic voltammetry of a preferred compound 8 according tothe present invention;

FIGS. 9 (a), (b) and (c) show, respectively, crystal structure of acompound 8 according to the invention; herringbone-like packing viewdown the b axis; and herringbone-like packing view down the longmolecular axis; wherein the H atoms the perfluorohexyl and n-butyl chainhave been removed for clarity.

FIG. 10 shows Atomic Force images of a 30 nm thick film of compound 8according to the present invention, grown on PMMA;

FIGS. 11 (a) and (b) show electrical characteristics for OTFTscomprising a 30 nm thick film of compound 8;

FIGS. 12 (a), (b) and (c) show a schematic view, opto-electronictransfer curves and an optical microscope image of a working OLET devicecomprising a 30 nm thick film of compound 8.

According to an aspect of the present invention, a compound of formula(I) or (II) is provided:

herein:

R¹, R² independently of each other, are selected in the group consistingof hydrogen, C₁-C₄₀ linear or branched alkyl groups, C₂-C₄₀ linear orbranched alkenyl groups, C₂-C₄₀ linear or branched alkynyl groups,C₁-C₄₀ linear or branched heteroalkyl groups, C₂-C₄₀ linear or branchedheteroalkynyl groups, C₂-C₄₀ linear or branched heteroalkynyl groups,C₃-C₄₀ linear or branched cycloalkyl groups, C₂-C₄₀ heterocycloalkylgroups, C₂-C₄₀ linear or branched alkylcarboxylic groups, C₂-C₄₀ linearor branched alkylcarboxamide groups, C₂-C₄₀ linear or branchedalkylimino groups, C₁-C₄₀ linear or branched alkylsulphonic groups,C₁-C₄₀ linear or branched alkyl nitrile groups;

Ar, Ar′, Ar″, independently of each other, are selected in the groupconsisting of monocyclic aryl groups, substituted monocyclic arylgroups, polycyclic aryl groups, substituted polycyclic aryl groups,monocyclic heteroaryl groups, substituted monocyclic heteroaryl groups,polycyclic heteroaryl groups, substituted polycyclic heteroaryl groupsand combinations thereof as dimers, trimers and tetramers;

R³ is selected in the group consisting of hydrogen, halogen, C₁-C₂₀linear or branched alkyl groups, C₂-C₂₀ linear or branched alkenylgroups, C₂-C₂₀ linear or branched alkynyl groups, C₁-C₂₀ linear orbranched heteroalkyl groups, C₂-C₂₀ linear or branched heteroalkenylgroups, C₂-C₂₀ linear or branched heteroalkynyl groups, C₃-C₂₀ linear orbranched cycloalkyl groups, C₂-C₂₀ heterocycloalkyl groups, C₂-C₂₀linear or branched alkylcarboxylic groups, C₂-C₂₀ linear or branchedalkylcarboxamide groups, C₂-C₂₀ linear or branched alkylimino groups,C₁-C₂₀ linear or branched alkylsulphonic groups, C₁-C₂₀ linear orbranched alkyl nitrile groups;

n, r, independently of each other, are integers between 1 and 50;

p is an integer between 0 and 5; and

T is a terminal unit of the compound and is selected among C₁-C₄₀ linearor branched alkyl groups, C₂-C₄₀ linear or branched alkenyl groups,C₂-C₄₀ linear or branched alkynyl groups, C₁-C₄₀ linear or branchedheteroalkyl groups, C₂-C₄₀ linear or branched heteroalkenyl groups,C₂-C₄₀ linear or branched heteroalkynyl groups, C₃-C₄₀ linear orbranched cycloalkyl groups, C₂-C₄₀ heterocycloalkyl groups, C₂-C₄₀linear or branched alkylcarboxylic groups, C₂-C₄₀ linear or branchedalkylcarboxamide groups, C₂-C₄₀ linear or branched alkylimino groups,C₁-C₄₀ linear or branched alkylsulphonic groups, C₁-C₄₀ linear orbranched alkyl nitrile groups, monocyclic aryl groups, substitutedmonocyclic aryl groups, polycyclic aryl groups, substituted polycyclicaryl groups, monocyclic heteroaryl groups, substituted monocyclicheteroaryl groups, polycyclic heteroaryl groups, substituted polycyclicheteroaryl groups, benzyl groups and substituted benzyl groups andcombinations thereof as dimers, trimers and tetramers;

wherein for values of p=0, T is different from Ar′, and for values of pfrom 1 to 5, T is different from Ar″;

with the exception of compounds of formula A:

wherein R₄ is selected in the group consisting of hydrogen and C₁-C₄alkyls; and

R₅ is selected in the group consisting of monocyclic aryl groups andsubstituted monocyclic aryl groups;

and with the exception of compounds of formula B:

wherein R₆ is selected in the group consisting of isopropyl, cyclopropyland terbutyl groups, R₇ is selected in the group consisting of phenyl,2-fluorphenyl, 3-fluorphenyl, 4-fluorphenyl, 2-chlorphenyl,3-chlorphenyl, 4-chlorphenyl, 2-methylphenyl, 3-methylphenyl,4-methylphenyl, 2-trifluoromethylphenyl, 3-trifluormethylphenyl,4-trifluormethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl,4-methoxyphenyl, 2,4-dichlorphenyl, 2,4,6-trimethylphenyl, 2-thienyl,3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl and R₁₈ is selected in thegroup consisting of hydrogen, fluorine, chlorine, methyl or methoxygroups.

In the present description and in the claims:

-   -   a “heteroalkyl group” is intended to include, for example, a        halogenoalkyl group, a hydroxyalkyl group, a alkoxyalkyl group;    -   a “heteroalkenyl group” is intended to include, for example, a        halogenoalkenyl group, a hydroxyalkenyl group, a alkoxyalkenyl        group;    -   a “heteroalkynyl group” is intended to include, for example, a        halogenoalkynyl group, a hydroxyalkynyl group, a alkoxyalkynyl        group.

The value of p is preferably 0, 1 or 2.

The values of n and r are preferably comprised between 2 and 50, morepreferably between 2 and 30, even more preferably between 2 and 10.

When p assumes the values of 0, then n is particularly preferablycomprised between 2 and 50, more preferably between 2 and 30, even morepreferably between 2 and 10.

Preferably, R³ is hydrogen.

Preferably, Ar, Ar′, Ar″, and T when aromatic, independently of eachother, are selected in the group consisting of unsubstituted orsubstituted C₆-C₅₀ monocyclic aryl groups, C₁₀-C₅₀ polycyclic arylgroups, C₁₀-C₅₀ substituted polycyclic aryl groups, unsubstituted orsubstituted monocyclic C₁-C₅₀ heteroaryl groups, C₆-C₅₀ polycyclicheteroaryl groups, C₆-C₅₀ substituted polycyclic heteroaryl groups andcombinations thereof as dimers, trimers and tetramers.

The preferred substituents of said monocyclic aryl groups, polycyclicaryl groups, monocyclic heteroaryl groups, polycyclic heteroaryl groupsof Ar, Ar′, Ar″ and T, are selected among halogens, alkyl, alkenyl,alkynyl or heteroalkyl groups. More preferably, said substituent groupsare selected in the group consisting of linear or branched C₁-C₁₂ alkyl,linear or branched C₂-C₁₂ alkenyl, linear or branched C₂-C₁₂ alkynyl,C₁-C₁₂ perfluoroalkyl, C₁-C₁₂ oxyalkyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂thioalkyl, C₁-C₁₂ haloalkyl, C₂-C₁₂ carboxyalkyl groups, C₁-C₁₂silicioalkyl groups.

Independently on the Ar, Ar′ and Ar″ selection, the terminal group T ispreferably selected in the group consisting of C₁-C₂₀ linear or branchedalkyl groups, C₂-C₂₀ linear or branched alkenyl groups, C₂-C₂₀ linear orbranched alkynyl groups, C₁-C₂₀ fluoroalkyl groups, C₁-C₂₀ thioalkylgroups, C₁-C₂₀ silicioalkyl groups, C₁-C₂₀ alkylamino groups, C₂-C₂₀alkylimino groups, phenyl groups, phenyl groups substituted with atleast one C₁-C₁₀ alkyl group and/or with at least one C₁-C₁₀ heteroalkylgroups, thienyl groups, thienyl groups substituted with at least oneC₁-C₁₀ allyl group and/or with at least one C₁-C₁₀ heteroalkyl groups,naphthalene, substituted naphthalene, antracene, substituted antracene,C₄-C₂₀ tricyclic heteroaryl groups.

More preferably, the terminal group T is selected in the groupconsisting of C₁-C₁₀ alkyl groups, C₁-C₁₀ perfluoroalkyl groups, C₂-C₁₀alkenyl groups, phenyl groups, substituted phenyl groups, thienylgroups, substituted thienyl groups, pyridine, thiazole, benzodithiazole,thienothiophene, dithienothiophene, dibenzothiophene, fluorene,naphthalene, antracene, substituted naphthalene, substituted antracene,xantines and alkylimino groups.

According to an aspect of the present invention, the compounds offollowing formulas (Ia) and (IIa) are provided, which correspond tothose of formulas (I) and (II), wherein p is equal to 0 and R³ ishydrogen:

wherein R¹, Ar, Ar′, T and n are as above defined.

In the present description and in the claims, the curved lines informulas (I), (Ia), connecting the Ar moiety to the thienoimide unit,indicate that said Ar moiety forms a fused ring system with saidthienoimide unit.

In addition, as usual in chemical drawing practice, in the presentdescription and in the claims the bond lines crossing the thiophenedouble bond in formulas (II), (IIa), indicates that the (Ar′)_(n) moietymay be bound to any of the 2 or 3 position in the thiophene ring and isnot fused thereto. Preferably, the (Ar′)_(n) moiety is bound to the 2position of the thiophene ring.

In formulas (I) and (Ia), the (Ar′)_(n) and (Ar″)_(r) moieties may bebound to any position of the Ar moiety that is fused to thethieno(bis)imide unit.

In formulas (Ia) and (IIa) the integer n is preferably comprised between1 and 30, more preferably between 2 and 30, even more preferably between2 and 10.

The compounds according to the invention wherein n is 2 arecharacterized by an advantageously high solubility in a number ofsolvents, for example dichloromethane, dimethyl sulfoxide,tetrahydrofuran, allowing for high level purification and easy solutionprocessing.

Preferably, the Ar′ is a unit selected among the following groups (a),(b), (c), (d), (e), (f), (g), (h), (i), (l), (m), (n), (o), (p), (q),(r):

wherein A is selected in the group consisting of S, O Se, atoms and SO,SO₂, R¹⁴—P═O, P—R¹⁴, N—R¹⁵, Si(R¹⁵)₂ groups;

D is selected in the group consisting of C, S, O Se, atoms and SO, SO₂,R¹⁴—P═O, PR¹⁴, BR¹⁴, N—R¹⁵, Si(R¹⁵)₂ groups;

B, C, independently of each other, are selected in the group consistingof C, N atoms;

E is selected in the group consisting of C(R¹⁵)₂, S, O, and NR¹⁵ group;

R⁸, R⁹, R¹⁰, R¹¹, R¹² and R¹³, independently of each other, are selectedin the group consisting of hydrogen, halogens, C₁-C₂₀ linear or branchedalkyl groups, C₂-C₂₀ linear or branched alkenyl groups, C₂-C₂₀ linear orbranched alkynyl groups, C₁-C₂₀ linear or branched heteroalkyl groups,C₂-C₂₀ linear or branched heteroalkenyl groups, C₂-C₂₀ linear orbranched heteroalkynyl groups, C₃-C₂₀ cycloalkyl groups, C₂-C₂₀ linearor branched heterocycloalkyl groups, C₂-C₂₀ linear or branchedalkylcarboxylic groups, C₂-C₂₀ linear or branched alkylcarboxamidegroups, C₂-C₂₀ linear or branched alkylimino groups, C₁-C₂₀ linear orbranched alkylsulphonic groups, C₁-C₂₀ linear or branched alkyl nitrilegroups, C₅-C₄₀ aryl groups, C₁-C₄₀ heteroaryl groups, C₆-C₄₀ alkylarylgroups;

R¹⁴, R¹⁵ independently of each other, are selected in the groupconsisting of hydrogen, C₁-C₂₀ linear or branched alkyl groups, C₂-C₂₀linear or branched alkenyl groups, C₂-C₂₀ linear or branched alkynylgroups, C₁-C₂₀ linear or branched heteroalkyl groups, C₂-C₂₀ linear orbranched heteroalkenyl groups, C₂-C₂₀ linear or branched heteroalkynylgroups, C₃-C₂₀ linear or branched cycloalkyl groups, C₂-C₂₀ linear orbranched heterocycloalkyl groups, C₂-C₂₀ linear or branchedalkylcarboxylic groups, C₂-C₂₀ linear or branched alkylcarboxamidegroups, C₂-C₂₀ linear or branched alkylimino groups, C₁-C₂₀ linear orbranched alkylsulphonic groups, C₁-C₂₀ linear or branched alkyl nitrilegroups, C₅-C₄₀ aryl groups, C₁-C₄₀ heteroaryl groups, C₆-C₄₀ alkylarylgroups.

In formulas (h), (i), (l), (m), (n), (o), (p), (q), (r), it is meantthat the substituent group may be bound to any carbon position of anyring forming the dclocalized system.

Examples of the above described groups of formula (a)-(r) are forexample the following:

In other preferred embodiments of the present invention, the Ar′ moietymay be a dimer comprising a thiophene, thiazole, furane, benzothiazole,thienothiophene or phenyl unit that is linked to another aryl unit, suchas the above represented (a)-(r) groups, like in the following formulas(s) and (t):

wherein W is a moiety selected in the group consisting of the aboveindicated groups (a) to (r), and R¹⁶ is a moiety selected in the samegroup as R⁸—R¹³.

More preferably, the Ar′ group may be a dimer comprising a thiopheneunit that is α-linked to a polycyclic or oligomeric unit such as in thefollowing (Ar′)_(n) moieties of formula (u), (v), (w), (x) and (y):

wherein R⁸, R⁹ and n have the above described meanings.

In an embodiment of the invention, Ar′ is a thiophene unit orsubstituted thiophene unit, wherein the (Ar′)_(n) moiety is a linearchain of a-linked thiophene units or substituted thiophene units.

The Ar moiety fused to the thienoimide unit of the compounds of formulas(I) and (Ia) according to the present invention may be advantageouslyformed of one, two or three aromatic rings.

Preferably, in formulas (I), (Ia), Ar is selected in the groupconsisting of the following rings (α), (β), (γ), (δ), (ε), (ζ), (η),(θ), (

):

wherein X is selected in the group consisting of S, SO, SO₂, O, Si, Sc,NR¹⁷,

Y is selected in the group consisting of C and N;

R¹⁷ is selected in the group consisting of hydrogen, C₁-C₂₀ linear orbranched alkyl groups, C₂-C₂₀ linear or branched alkenyl groups, C₂-C₂₀linear or branched alkynyl groups, C₁-C₂₀ linear or branched heteroalkylgroups, C₂-C₂₀ linear or branched heteroalkenyl groups, C₂-C₂₀ linear orbranched heteroalkynyl groups, C₃-C₂₀ linear or branched cycloalkylgroups, C₂-C₂₀ heterocycloalkyl groups, C₂-C₂₀ linear or branchedalkylcarboxylic groups, C₂-C₂₀ linear or branched alkylcarboxamidcgroups, C₂-C₂₀ linear or branched alkylimino groups, C₁-C₂₀ linear orbranched alkylsulphonic groups, C₁-C₂₀ linear or branched alkyl nitrilegroups, C₅-C₄₀ aryl groups, C₁-C₄₀ heteroaryl groups, C₆-C₄₀ alkylarylgroups

Specific examples of compounds of formula (IIa) according to the presentinvention are for example the following compounds 6 and 8-18:

Without wishing to limit the present invention to any theory, it isbelieved that the thiopheneimide moiety due to its strongelectrowithdrawing effect can increase the overall electron affinity ofπ-conjugated materials promoting the electron charge transportcapability. On the other hand, the opposite terminal groups may beexploited to tune the dipole moment, the HOMO LUMO energy levels andorbital distribution and the packing modality, this ultimatelyinfluencing the functional properties of the resulting materials.Compounds 6 and 8 are particularly advantageous, being additionallyprovided with good electroluminescence, as shown in the followingexamples.

Among the main advantages of such compounds with respect to otherclasses of n-type materials are to be mentioned the easy accessibilityand structural versatility.

The thienoimide moiety can be coupled to selected π-conjugated cores bycross-couplings under conventional or microwave-assisted heating asdescribed below or by direct arylation reaction.

The easy accessibility of the compounds according to the invention alsoallows an easy modification of the oligomer size, and degree and type ofmolecular functionalization, which in turn permits application fineproperty-specific design toward the targeted applications.

The compounds according to the present invention can be obtained withelectronic level of purity by chromatography, crystallization andsublimation, with unambiguous molecular structure determination throughclassic analytical methods.

Contrarily to the thiophene-3,4-imide based polymers, bithiophene-imidepolymers and perylene tetrarboxylic diimidc systems according to theprior art, this class of materials can be prepared with highreproducibility from batch to batch, which is crucial to achieve deviceswith reproducible responses.

According to still another aspect of the invention, it is provided aprocess for the production of a compound according to the invention,wherein the process comprises reiterative halogenation of aromaticcompounds and cross-coupling reactions.

The processes according to the present invention are preferablycatalized by palladium.

The compounds according to the invention of formulas (I), (II) may beobtained starting from an aromatic dihalide, such as in the followingSchemes 1 and 2:

wherein Z is selected among halogen atoms, such as Br, I; M is anorganometal compound such as B(OR′)₂ and SnR″₃ wherein R′ is an hydrogenor an alkyl moiety and R″ is an alkyl moieties; and [cat] is a palladiumbased catalyst. Alternatively, Z can be hydrogen and can undergo directCH arylation reaction under Pd catalysis.

Scheme 1a shows possible synthetic approaches for the preparation of thestarting materials of the process of scheme 1, wherein Z is halogen andNZS means halogenated succinimide. Depending on the type of the fusedheterocycle, pathway a or b should be selected.

The compounds of formulas (Ia), (IIa), may be obtained according to thepresent invention by means of processes as outlined in the followingSchemes 3 and 4:

wherein Z is selected among halogen atoms, such as Br, I; M is anorganometal compound such as B(OR′)₂ and SnR″₃ wherein R′ is selected inthe group consisting of hydrogen and alkyl moieties, and R″ is selectedin the group consisting of alkyl moieties; and [cat] is a palladiumbased catalyst. For example, tetrakis triphenylphosphine palladium (0)can be used as catalyst.

In another aspect thereof, the present invention relates to asemiconductor material, comprising at least one compound according toformulas (I) and/or (II). Preferably, said semiconductor materialcomprises at least one compound according to formulas (Ia) and/or (IIa).

In an embodiment thereof, said semiconductor material comprises one ormore of compounds 6 and 8 to 18, preferably compounds 6 and/or 8.

According to another aspect, the invention relates to an electronicdevice comprising a semiconductor layer in contact with a number ofelectrodes, wherein the semiconductor layer includes at least onecompound according to formulas (I) and/or (II). Preferably, saidsemiconductor layer comprises at least one compound according toformulas (Ia) and/or (IIa). More preferably, said semiconductor layer,comprises at least one compound selected among compounds 6 and 8 to 18.

In an embodiment thereof, said semiconductor layer comprises compound 6and/or compound 8.

Preferably, said electronic device comprising a semiconductor layerincluding the compounds according to the present invention is selectedamong optical devices, electrooptical devices, field effect transistors,integrated circuit, thin film transistors, organic light-emittingdevices, and organic solar cells.

Particularly, thin films of the thienoimide based materials according tothe invention can be used as active layers in OFETs and OLET devices asdemonstrated in the following examples. They can be used as electron- orhole-transporting layer or ambipolar semiconductor in single layer OFET,as multifunctional electron- and hole-transporting and light emittinglayer in single layer OLET, and as hole or electron transporting layerin multi-layer OLET.

Finally, applications of compounds and materials according to thepresent invention in organic photovoltaics can be envisaged.

In the following examples, all ¹H, ¹³C, and ¹⁹F NMR spectra wererecorded at room temperature on a Varian Mercury 400 spectrometeroperating at 400 MHz (¹H) and 100.6 MHz (¹³C). Chemical shifts werecalibrated using the internal CDCl₃, acetone-d₆ or CD₂Cl₂ resonancewhich were referenced to TMS. In the ¹⁹F NMR spectra 0.5% fluorobenzenewas added as an internal standard. The fluorobenzene was referenced toCFCl₃.

Mass spectra were collected on an ion trap Finningan Mat GCQspectrometer operating in electron impact (EI) ionization mode. Eachsample was introduced to the ion source region of the GCQ via a directexposure probe (DEP).

Melting points were determined on a ‘hot-stage’ apparatus where themelting process was observed with the aid of a microscope.

UV-Vis spectra were recorded using a Perkin Elmer Lambda 20spectrometer. Photoluminescence spectra were obtained with a PerkinElmer LS50B spectrofluorometer using an excitation wavelengthcorresponding to the maximum absorption lambda.

Differential Scanning calorimetry (DSC) analysis were performed by usinga Thass DSC-XP-10 instrument under atmospheric conditions.

5-tributylstannyl-2,2′-bithiophene, 2-hexyl-5-tributhylstannyl-thiophene2-perfluorohexyl-5-tributhylstannyl-thiophene were purchased fromSigma-Aldrich Co. Thiophene-2,3-dicarboxylic anhydride, was preparedaccording to already reported procedures.

Cyclic Voltammetry measurements have been performed at room temperature,after Ar purging, with an AMEL 5000 electrochemical system in CH₂Cl₂(Carlo Erba RPE, distilled over anhidrous P₂O₅ and stored under Arpressure) and 0.1 M (C₄H₉)₄NClO₄ (Fluka, puriss. crystallized frommethanol and vacuum dried). The electrochemical cell was in threecompartment shape, with Pt semi sphere electrode (diameter 2 mm), Ptwire counter electrode and aqueous KCl Saturated Calomel Electrode(SCE=0.47 V vs. ferrocene/ferricinium). The concentration of thecompounds were 1.1 mmol L⁻¹.

AFM on vacuum sublimed films was performed by using a NT-MDT Solver ProAFM atomic force microscope in tapping mode.

EXAMPLE 1 Synthesis of2-(5″-hexyl-2,2′:5′,2″-terthiophene-5-yl)-5-butyl-5H-thieno[3,2-c]pyrrole-4,6-dione,Compound 6:

The synthesis was performed according to the below reported scheme.

Step (a): Synthesis of2-([2,2′-bithiophen]-5-yl)-5-butyl-4H-thieno[2,3-c]pyrrole-4,6(5H)-dione,3

To a refluxing toluene solution (8 ml) of compound 1 (82 mg, 0.28 mmol)and in situ-prepared Pd(AsPh₃)₄ (8 mol %, 11 mg of Pd₂dba₃ and 27 mg ofAsPh₃) under N₂ atmosphere, 5-(tributylstannyl)-2,2′-bithiophene, 2 (135mg, 0.3 mmol) in toluene (0.5 ml), was added dropwise. The solution wasrefluxed for 6 h, then the solvent was removed under vacuum and thecrude product purified by flash chromatography on silica gel by using asolution of pet. eth./DCM/AcOE=90:5:5 as eluent. Compound 3 was isolatedas a orange powder (83 mg, yield 79%) and used for the following stepwithout further purification. MS (70 eV, EI): m/z 373 (M.⁺¹). ¹H NMR(CDCl₃, TMS/ppm) δ: 7.29 (s, 1H), 7.28 (dd, ³J=5.2 Hz, ⁴J=1.2 1H), 7.23(m, 2H), 7.12 (d, ³J=3.6 Hz 1H), 7.05 (dd, ³J=5.2 Hz, ³J=4.8 1H), 3.60(t, 2H), 1.63 (m, 2H), 1.36 (m, 2H), 0.95 (t, 3H). ¹³C NMR (CDCl₃,TMS/ppm): 163.9, 162.8, 149.9, 145.2, 139.3, 137.1, 136.1, 133.6, 128.1,126.7,125.5, 124.7,124.5, 116.3, 38.3, 30.8, 20.0, 13.6.

Step (b): Synthesis of2-(5′-bromo-[2,2′-bithiophen]-5-yl)-5-butyl-4H-thieno[2,3-c]pyrrole-4,6(5H)-dione, 4

Compound 3 (90 mg, 0.24 mmol) obtained as in step (a) was dissolved in 8ml of a 1:1 mixture of dichloromethane and acetic acid solution. NBS (50mg, 0.28 mmol) was added and the reaction mixture was stirred at roomtemperature over night in darkness. The yellow solution so obtained wasthen diluted with 10 ml of water, extracted with dichloromethane, washedwith 10% NaHCO₃, and water. The organic phase was dried over anhydroussodium sulfate and evaporated and the crude product purified by flashchromatography on silica gel by using pet. eth./AcOEt 94:6 to 80:20 aseluent. Compound 4 was isolated as a orange powder (97% yield). M.p.153° C., MS (70 eV, EI): m/z 451, 453 (M.⁺¹). ¹H NMR (CDCl₃, TMS/ppm) δ:7.29 (s, 1H), 7.21 (d, ³J=4.0 Hz, 1H), 7.05 (d, ³J=3.6 Hz, 1H), 7.00 (d,³J=4.0 Hz, 1H), 6.96 (d, ³J=4.0 Hz, 1H), 3.60 (t, 2H), 1.62 (m, 2H),1.36 (m, 2H), 0.95 (t, 3H). ¹³C NMR (CDCl₃, TMS/ppm) 163.9, 162.7,149.5, 145.2, 138.1, 137.6, 137.4, 134.0, 130.9, 126.7, 124.8, 124.7,116.7, 112.3, 38.3, 30.8, 20.0, 13.6.

Step (c): Synthesis of2-(5″-hexyl-2,2′:5′,2″-terthiophene-5-yl)-5-butyl-5H-thieno[3,2-c]pyrrole-4,6-dione:6

To a refluxing toluene solution (12 ml) of Pd(AsPh₃)₄ (8 mol %, preparedin situ) and compound 4 (0.22 mmol), obtained as in step (b), under N₂atmosphere, compound 5 (0.26 mmol) diluted in 3 ml of toluene was addeddropwise. The solution was refluxed for 8 h, then the solvent wasremoved under vacuum. The crude was purified by flash chromatography onsilica gel, eluent: pet. eth./Ethyl Acetate 95:5 to 0:100, followed bycrystallization.

Compound 6 was obtained as an orange powder (68% yield). M.p. 178°(K→LC), 260°; MS (70 eV, EI): m/z 539 (M.⁺¹). ¹H NMR (CDCl₃, TMS/ppm):7.28 (s, 1H), 7.22 (d, ³J=3.6 Hz, 1H), 7.10 (d, ³J=3.6 Hz 1H), 7.09 (d,³J=4.0 Hz, 1H), 7.01 (d, ³J=4.0 Hz, 1H), 7.00 (d, ³J=3.6 Hz, 1H), 7.69(d, ³J=3.6 Hz, 1H), 3.60 (t, 2H), 2.80 (t, 2H), 1.66 (m, 4H), 1.35 (m,8H), 0.92 (m, 6H). ¹³C NMR (CDCl₃, TMS/ppm): 163.9, 162.8, 149.9, 146.2,145.3, 139.2, 138.2, 137.0, 134.0, 133.3, 126.7, 125.2, 124.9, 124.2,123.8, 123.7, 116.2, 38.3, 31.5, 30.9, 30.2, 28.7, 22.6, 20.0, 14.1,13.6. Anal. Calcd for C₂₈H₂₉NO₂S₄ (539.80): C, 62.30; H, 5.42. Found: C,62.24; H, 5.49.

In the DSC thermograms of compound 6 (second run, 10° C./min) in air,compound 6 shows the melting transition at about 157° C., followed by atransition LC1→LC 2 at 179° C. Finally, isotropization occurred at 246°C.

Optical spectroscopy of compound 6 was performed. FIG. 1( a) shows theabsorption and emission spectra of compound 6 in CH₂Cl₂ solution andFIG. 1( b) the absorption and emission spectra of compound 6 as a vacuumsublimed film of 30 nm thickness.

CVs of compound 6 (1.1 mmol l⁻¹) at 100 mV/s in CH₂Cl₂, 0.1 mol l⁻¹(C₄H₉)₄NClO₄ is shown in FIG. 2. The voltammogram of compound 6 showstwo oxidation waves at E°_(ox1)=1.05 V and E°_(ox2)=1.28 V. On the otherhand, it shows a quasi-reversible reduction wave at E°_(red1)=−1.24 V,and an irreversible reduction wave at E_(red) ^(1/2)=−1.75 V due to theoligothiophene moiety.

Table 1 reports a summary of the optoelectronic properties measured forcompound 6.

λ_(abs) λ_(abs) λ_(PL) nm^(a) λ_(PL) E_(g) ^(opt) Film^(b) film^(b) HOMOeV^(c) LUMO E_(g) ^(ec) Comp. (theor) nm^(a) eV (nm) (nm) (theor)^(c)eV^(c) (theor) eV compound 6 447 631 2.77 340 584/611 −5.73 −3.42 2.31(450) (−5.14) (−2.31) ^(a)in CH₂Cl₂, ^(b)30 nm thick film, ^(c)E_(HOMO)= e (4.68 − E⁰ _(ox)); E_(LUMO) = e (4.68 − E⁰ _(red))

X-ray diffraction analysis was carried out by means of a PANalyticalX'Pert diffractometer equipped with a copper anode (λ_(mean)=0.15418 nm)and a fast X'Celerator detector. Step 0.05° (2theta scale), countingtime 400 sec. Films grown on Si/SiO2 substrates or on OFET device(counting time 1200 sec) were directly investigated.

FIG. 3 shows the results of a X-ray diffraction analysis of compound 6.FIG. 4( a) shows an XRD pattern obtained from a 30 nm film of compound 6on SiO₂ substrate (counting time 400 sec/step) and FIG. 4( b) shows anXRD pattern obtained from film grown on a PMMA substrate of an OFETdevice (counting time 1200 sec/step).

FIG. 4 is the atomic force microscope image showing the morphology of athin film (30 nm) of compound 6 grown on a 450 nm thick layer of PMMAwhich is deposited on a ITO layer.

EXAMPLE 2 Fabrication and Optoelectronic Measurements of Field EffectTransistor (OFET)

Organic thin film transistors were fabricated in bottom gate-top contactgeometry. An ITO substrate was cleaned be means of two sonicationcycles, first in acetone and then 2-isopropanol, for 10 minutes each.Then a 450 nm thick dielectric layer of PMMA was grown by spin-coatingon top of the clean ITO substrate. The relative electric permittivity εwas 3.6 at 100 Hz. The PMMA layer was then thermally annealed in a glovebox at 120° C. (i.e., around 10° C. above the glass transitiontemperature for PMMA) for 15 hours under inert atmosphere. (CPMMA=7.08nF/cm²).

Then, an organic thin film layer consisting of compound 6 was grown onthe top of said dielectric layer by vacuum sublimation in a vacuumchamber, with a deposition rate of 0.1 Å/s, at a base pressure of 10⁻⁶mbar. The substrate temperature during the film deposition was kept atroom temperature (RT).

Then, gold drain and source electrodes were made on top of the organicthin film by evaporation through a shadow mask. The thickness of saidgold drain and source electrodes was 50 nm, while the channel length (L)and the channel width (W) were 70 μm and 12 mm, respectively.

The electrical characteristics of such a transistor were then measured.All opto-electronic measurements were carried out in an MBraun nitrogenglove box using a standard SUSS Probe Station equipped with a Hamamatsuphotodiode for light detection.

The mobility values in saturation were calculated from the locus curvesusing the standard equations:

μ=L/(W*C)Â2  [eq. 1]

wherein A is the angular coefficient of the line fitting the square rootof the drain current vs the applied voltage, L is the channel length, Wthe channel width and C is the transistor dielectric capacitance.

FIG. 5 (a) shows the output curve of such transistor comprising anorganic layer consisting of compound 6. FIG. 5( b) shows the transfercurve of such transistor comprising an organic layer consisting ofcompound 6.

EXAMPLE 3 Fabrication and Optoelectronic Measurements of Organic LightEmitting Transistor (OLET)

An organic light emitting transistor was fabricated, having theconfiguration of the transistor of example 2, therefore the samefabrication procedure was followed.

The electrical characteristics of such a transistor were then measuredwith the same methods as for example 2, and transfer curves wereobtained.

Table 2 reports a summary of the electrical parameters measured for a 30nm layer formed of compound 6 in an OLET device.

TABLE 2 OLET emission μ_(h) I_(on)/ μ_(e) power Comp. (cm²V⁻¹S⁻¹) V_(T)^(P)/V I_(off) (cm²V⁻¹s⁻¹) V_(T) ^(N)/V (nW) com- 3.1 × 10⁻³ −17.5 10⁴2.8 × 10⁻⁵ 10.9 8 pound 6

EXAMPLE 4 Synthesis of2-(5″-(perfluorohexyl)-2,2′:5′,2″-terthiophene-5-yl)-5-butyl-5H-thieno[3,2-c]pyrrole-4,6-dione,Compound 8

The synthesis was performed according to the below reported scheme:

Compounds 3 and 4 were obtained as described in Example 1, steps (a) and(b).

Step (d): Synthesis of2-(5″-(perfluorohexyl)-2,2′:5′,2″-terthiophene-5-yl)-5-butyl-5H-thieno[3,2-c]pyrrole-4,6-dione,8

To a refluxing toluene solution (8 ml) of Pd(AsPh₃)₄ (8 mol %, in situprepared) and compound 4 (0.237 mmol) under N₂ atmosphere, compound 7(0.26 mmol) diluted in 0.5 ml of toluene was added dropwise. Thesolution was refluxed for 8 h, then the solvent was removed undervacuum. The crude was purified by flash chromatography on silica gel,eluent DCM, followed by crystallization from toluene.

Compound 8 was obtained as an orange powder (74% yield). M.p. 182°(K→LC), 320° C. (LC→I), MS (70 eV, EI): m/z 773 (M.⁺¹). ¹H NMR (CDCl₃,TMS/ppm) δ: 7.36 (d, ³J=3.6 Hz 1H), 7.31 (s, 1H), 7.25 (d, ³J=4.4 Hz1H), 7.17 (m, 4H), 3.61 (t, 2H), 1.63 (m, 2H), 1.36 (m, 2H), 0.95 (t,3H). ¹³C NMR (CDCl₃, TMS/ppm): 163.9, 162.7, 149.5, 145.3, 141.8, 138.3,137.5, 136.7, 135.1, 134.3, 131.1, 126.8, 126.1, 125.4, 125.0, 123.7,116.5, 38.4, 30.8, 20.0, 13.6. ¹⁹F NMR) (CDCl₃, C₆H₅F/ppm): −80.2 (t,3F), −100.8 (m, 2F), −121.0 (m, 4F), −122.3 (broad singlet, 2F), −125.6(m, 2F). Anal. Calcd for C₂₈H₁₆F₁₃NO₂S₄ (773.67): C, 43.47; H, 2.08.Found: C, 43.52; H, 2.02.

The DSC thermograms of compound 8 (second run, 10° C./min) in air wereobtained. Compound 8 shows a crystal-liquid transition at about 100° C.(not reversible), followed by a transition to isotropic phase at 297° C.

Optical spectroscopy of compound 8 was performed. FIG. 7( a) shows theabsorption and emission spectra of compound 8 in CH₂Cl₂ solution andFIG. 7( b) the absorption and emission spectra of compound 8 as a vacuumsublimed film of 30 nm thickness.

CVs of compound 8 (1.1 mmol l⁻¹) at 100 mV/s in CH₂Cl₂, 0.1 ml l⁻¹(C₄H₉)₄NClO₄ is shown in FIG. 8. The voltammogram of compound 8 shows aquasi-reversible reduction wave at E°_(red1)=−1.24 V, and anirreversible reduction wave at E^(1/2) _(red2)=−1.58 V. Oxidation wavesare shown E°_(ox1)=−1.29 V and E°_(ox2)=−1.63 V.

Table 3 reports a summary of the optoelectronic properties measured forcompound 8.

TABLE 3 λ_(abs) nm^(a) λ_(PL) E_(g) ^(opt) λ_(abs) λ_(PL) HOMO LUMOE_(g) ^(ec) Comp. (theor) nm^(a) eV Film^(b) (nm) film^(b) (nm)eV^(c)(theor)^(c) eV^(c)(theor) eV Compound 8 433 (437) 580 2.83 361 580−5.99 (−5.43) −3.42 (−2.47) 2.57 ^(a)in CH₂Cl₂, ^(b)30 nm thick film,^(c)E_(HOMO) = e (4.68 − E⁰ _(ox)); E_(LUMO) = e (4.68 − E⁰ _(red))Single crystal XRD were registered for compound 8.

X-ray data were collected using a Bruker SMART Apex II CCD area detectordiffractometer with Mo—Kα (λ=0.71073 Å) as the incident radiation.Structures were solved using SIR 97 and were refined by full-matrixleast-squares on F_(o) ² using SHELXL97.

Crystal data for compound 8 were the following: C₂₈H₁₆F₁₃NO₂S₄,M=773.66, monoclinic, C2/c, a=109.92(2), b=5.7796(11), c=19.480(4) Å,β=97.866(3)°, V=12259.(4) Å³, Z=16, D_(c)=1.677 g cm⁻³, μ=0.419 mm⁻¹,T=293 K, λ(Mo—Kα)=0.71073 Å, data/parameters=10695/874, converging toR₁=0.1401, wR₂=0.3803 (on 4941 I>2σ(I) observed data); R₁=0.2049,wR₂=0.4287 (all data), residual electron density: 1.299 e Å³.

FIG. 9 (a) shows the crystal structure of compound 8, as derived fromthe above described single crystal XRD analysis. FIG. 9( b) showsherringbone-like packing view down the b axis; and FIG. 9 (c) showsherringbone-like packing view down the long molecular axis; wherein theH atoms the perfluorohexyl and n-butyl chain have been removed forclarity.

FIG. 10 is a 2D atomic force microscope image showing the morphology ofa 30 nm thick layer of compound 8, grown on a 450 nm thick layer of PMMAwhich is deposited on a ITO layer.

EXAMPLE 5 Fabrication and Optoelectronic Measurements of Field EffectTransistor (OFET)

Organic thin film transistors were fabricated in bottom gate-top contactgeometry. An ITO substrate was cleaned be means of two sonicationcycles, in acetone first and 2-isopropanol then, for 10 minutes each.Then a 450 nm thick dielectric layer of PMMA was deposited byspin-coating on top of the clean ITO substrate. The relative electricpermittivity ε was 3.6 at 100 Hz. The PMMA layer was then thermallyannealed in a glove box at 120° C. (i.e., around 10° C. above the glasstransition temperature for PMMA) for 15 hours under inert atmosphere.(CPMMA=7.08 nF/cm²).

Then, an organic thin film layer consisting of compound 8 was grown onthe top of said dielectric layer by vacuum sublimation in a vacuumchamber, with a deposition rate of 0.1 Å/s, at a base pressure of 10⁻⁶mbar. The substrate temperature during the film deposition was kept atroom temperature (RT).

Then, gold drain and source electrodes were made on top of the organicthin film by evaporation through a shadow mask. The thickness of saidgold drain and source electrodes was 50 nm, while the channel length (L)and the channel width (W) were 70 and 12 mm, respectively.

The electrical characteristics of such a transistor were then measured.All opto-electronic measurements were carried out in an MBraun nitrogenglove box using a standard SUSS Probe Station equipped with a Hamamatsuphotodiode for light detection.

The mobility values in saturation were calculated as described withreference to example 2.

FIG. 11 (a) shows the output curve of such transistor comprising anorganic layer consisting of compound 8. FIG. 11( b) shows the transfercurve of such transistor comprising an organic layer consisting ofcompound 8.

EXAMPLE 6 Fabrication and Optoelectronic Measurements of Organic LightEmitting Transistor (OLET)

An organic light emitting transistor was fabricated as described inexample 3.

FIG. 12( a) shows the schematic structure of the obtained OLET devicecomprising a semiconductor layer formed of compound 8.

The electrical characteristics of such a transistor were then measuredwith the same methods as for example 2, and opto-electronic transfercurves obtained are shown in FIG. 12( b) together with theelectroluminescence profile. FIG. 12 (c) shows an optical microscopeimage of a working OLET based on compound 8. The luminescence stripemoves along the device channel.

Table 4 reports a summary of the electrical parameters measured for a 30nm layer formed of compound 8 in an OLET device.

OLET μ_(h) V_(T) ^(P)/ I_(on)/ μ_(e) emission Comp. (cm²V⁻¹S⁻¹) VI_(off) (cm²V⁻¹s⁻¹) V_(T) ^(N)/V power (nW) comp. 8 1.4 × 10⁻⁵ −39.5 10⁴0.011 19.1 50

EXAMPLE 7 Synthesis of2-(5″-(1,3-dioxolan-2-yl)-[2,2′;5′,2″-terthiophen]-5-yl)-5-hexyl-4H-thieno[2,3-c]pyrrole-4,6(5H)-dione

Step a): Synthesis of 2-(thiophen-2-yl)-1,3-dioxolane, 19

A mixture of thiophene-2-carbaldehyde (1 g, 0.0089 mol), ethylene glycol(1.3 g, 0.02 mol), p-TsOH (0.022 g), in 9 ml of fluorobenzene wasstirred at reflux temperature under H₂O separation for 5 h. Distillationat 55° C. (0.1 mmHg) gave 1.06 g of 19 as an oil (76% yield).

¹H NMR (CDCl₃, TMS/ppm) δ 7.33 (m, 1H), 7.17 (m, 1H), 7.04 (d, ³J=4.0Hz, 2H), 6.00 (dd, ³J=3.6 Hz, ³J=3.2 Hz, 1H), 6.12 (s, 1H), 4.14 (m,2H), 4.02 (m, 2H).

Step b): Synthesis of(5-(1,3-dioxolan-2-yl)thiophen-2-yl)tributylstannane, 20

To an anhydrous solution of 19 (0.970 g, 0.0062 mol) in 15 ml of THF,BuLi (2.5 M in hexane) (3.0 ml, 0.0074 mol) was added dropwise at −78°C. under N₂ atmosphere. The mixture was stirred for 2 h and then, at thesame temperature, Bu₃SnCl (2.0 g, 0.0062 mol) was added dropwise. Thereaction was left under stirring at room temperature overnight. Thesolvent was removed under vacuum and then the crude product wasdissolved in ethyl ether and quenched with water. After extraction, theorganic phase was dried over Na₂SO₄ and the solvent was evaporated,obtaining compound 20 as a brown oil (2.7 g, yield=98%).

¹H NMR (CDCl₃, TMS/ppm) δ 7.27 (d, ³J=3.2 Hz, 1H), 7.05 (d, ³J=3.2 Hz,1H), 6.15 (s, 1H), 4.15 (m, 2H), 4.01 (m, 2H), 1.55 (m, 6H), 1.31 (m,6H), 1.08 (m, 6H), 0.89 (t, 9H).

Step c): Synthesis of2-(5″-(1,3-dioxolan-2-yl)-[2,2′:5′,2″-terthiophen]-5-yl)-5-hexyl-4H-thieno[2,3-c]pyrrole-4,6(5H)-dione,21

To a refluxing toluene solution (3 ml) of 22 (100 mg, 0.2 mmol) andin-situ prepared catalyst Pd(AsPh₃)₄ (8 mol %, i.e. 8 mg of Pd₂dba₃ and19 mg of AsPh₃ in 4 ml toluene) under N₂ atmosphere, 20 (102 mg, 0.23mmol) in toluene (1 ml), was added dropwise. The solution was refluxedfor 12 h then the solvent was evaporated and the crude product washedwith pentane. The solid obtained was purified by flash chromatography onsilica gel (elution with CH₂Cl₂). The fractions containing the productwere combined, the solvent evaporated, and the residue crystallized fromhot toluene to give an orange-red solid (60 mg, yield=54%).

M.p. 190° C. ELMS m/z 555 (M·⁺). λ

_(max) (CH₂Cl₂), 439 nm, λ

_(em) (CH₂Cl₂), 604 nm.

¹H NMR (CDCl₃, TMS/ppm) δ 7.30 (s, 1H), 7.24 (d, ³J=4.0 Hz, 1H), 7.13(d, ³J=4.0 Hz, 1H), 7.12 (d, ³J=4.0 Hz, 1H), 7.09 (d, ³J=4.0 Hz, 1H),7.07 (d, ³J=4.0 Hz, 1H), 7.06 (d, ³J=4.0 Hz, 1H), 6.09 (s, 1H), 4.15 (m,2H), 4.04 (m, 2H), 3.60 (t, 2H) 1.64 (m, 2H), 1.31 (m, 6H), 0.88 (t,3H).

¹³C NMR (CDCl₃, TMS/ppm) δ 163.9, 162.8, 149.7, 145.2, 141.2, 138.8,137.6, 137.2, 137.1, 135.1, 133.7, 127.0, 126.8, 125.3, 124.7, 124.5,123.6, 116.3, 100.1, 65.3, 38.6, 31.4, 28.8, 26.5, 22.5, 14.0.

1. A compound having formula selected in the group consisting of formula(I) and formula (II):

wherein: R¹, R² independently of each other, are selected in the groupconsisting of hydrogen, C₁-C₄₀ linear or branched alkyl groups, C₂-C₄₀linear or branched alkenyl groups, C₂-C₄₀ linear or branched alkynylgroups, C₁-C₄₀ linear or branched heteroalkyl groups, C₂-C₄₀ linear orbranched heteroalkenyl groups, C₂-C₄₀ linear or branched heteroalkynylgroups, C₃-C₄₀ linear or branched cycloalkyl groups, C₂-C₄₀heterocycloalkyl groups, C₂-C₄₀ linear or branched alkylcarboxylicgroups, C₂-C₄₀ linear or branched alkylcarboxamide groups, C₂-C₄₀ linearor branched alkylimino groups, C₁-C₄₀ linear or branched alkylsulphonicgroups, C₁-C₄₀ linear or branched alkyl nitrile groups; Ar, Ar′, Ar″,independently of each other, are selected in the group consisting ofmonocyclic aryl groups, substituted monocyclic aryl groups, polycyclicaryl groups, substituted polycyclic aryl groups, monocyclic heteroarylgroups, substituted monocyclic heteroaryl groups, polycyclic heteroarylgroups, substituted polycyclic heteroaryl groups and combinationsthereof as dimers, trimers and tetramers; R³ is selected in the groupconsisting of hydrogen, halogen, C₁-C₂₀ linear or branched alkyl groups,C₂-C₂₀ linear or branched alkenyl groups, C₂-C₂₀ linear or branchedalkynyl groups, C₁-C₂₀ linear or branched heteroalkyl groups, C₂-C₂₀linear or branched heteroalkenyl groups, C₂-C₂₀ linear or branchedheteroalkynyl groups, C₃-C₂₀ linear or branched cycloalkyl groups,C₂-C₂₀ heterocycloalkyl groups, C₂-C₂₀ linear or branchedalkylcarboxylic groups, C₂-C₂₀ linear or branched alkylcarboxamidegroups, C₂-C₂₀ linear or branched alkylimino groups, C₁-C₂₀ linear orbranched alkylsulphonic groups, C₁-C₂₀ linear or branched alkyl nitrilegroups; n, r, independently of each other, are integers between 1 and50; p is an integer between 0 and 5; and T is a terminal unit of thecompound and is selected among C₁-C₄₀ linear or branched alkyl groups,C₂-C₄₀ linear or branched alkenyl groups, C₂-C₄₀ linear or branchedalkynyl groups, C₁-C₄₀ linear or branched heteroalkyl groups, C₂-C₄₀linear or branched heteroalkenyl groups, C₂-C₄₀ linear or branchedheteroalkynyl groups, C₃-C₄₀ linear or branched cycloalkyl groups,C₂-C₄₀ heterocycloalkyl groups, C₂-C₄₀ linear or branchedalkylcarboxylic groups, C₂-C₄₀ linear or branched alkylcarboxamidegroups, C₂-C₄₀ linear or branched alkylimino groups, C₁-C₄₀ linear orbranched alkylsulphonic groups, C₁-C₄₀ linear or branched alkyl nitrilegroups, monocyclic aryl groups, substituted monocyclic aryl groups,polycyclic aryl groups, substituted polycyclic aryl groups, monocyclicheteroaryl groups, substituted monocyclic heteroaryl groups, polycyclicheteroaryl groups, substituted polycyclic heteroaryl groups, benzylgroups and substituted benzyl groups and combinations thereof as dimers,trimers and tetramers; wherein for values of p=0, T is different fromAr′, and for values of p from 1 to 5, T is different from Ar″; with theexception of compounds of formula A:

wherein R₄ is selected in the group consisting of hydrogen and C₁-C₄alkyls; and R₅ is selected in the group consisting of monocyclic arylgroups and substituted monocyclic aryl groups; and with the exception ofcompounds of formula B:

wherein R₆ is selected in the group consisting of isopropyl, cyclopropyland terbutyl groups, R₇ is selected in the group consisting of phenyl,2-fluorphenyl, 3-fluorphenyl, 4-fluorphenyl, 2-chlorphenyl,3-chlorphenyl, 4-chlorphenyl, 2-methylphenyl, 3-methylphenyl,4-methylphenyl, 2-trifluoromethylphenyl, 3-trifluormethylphenyl,4-trifluormethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl,4-methoxyphenyl, 2,4-dichlorphenyl, 2,4,6-trimethylphenyl, 2-thienyl,3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl and R₁₈ is selected in thegroup consisting of hydrogen, fluorine, chlorine, methyl or methoxygroups.
 2. A compound according to claim 1, wherein when p is 0, n isbetween 2 and
 50. 3. A compound according to claim 1 or 2, havingformula selected in the group consisting of formula (Ia) and formula(IIa)

wherein: Ar, Ar′ and Ar″, independently of each other, are selected inthe group consisting of C₆-C₅₃ unsubstituted and substituted monocyclicaryl groups, C₁₀-C₅₀ polycyclic aryl groups, C₁₀-C₅₀ substitutedpolycyclic aryl groups, unsubstituted and substituted monocyclic C₁-C₅₀heteroaryl groups, C₆-C₅₀ polycyclic heteroaryl groups, C₆-C₅₀substituted polycyclic heteroaryl groups; T is selected in the groupconsisting of C₁-C₂₀ linear or branched alkyl groups, C₂-C₂₀ linear orbranched alkenyl groups, C₂-C₂₀ linear or branched alkynyl groups,C₁-C₂₀ fluoroalkyl groups, C₁-C₂₀ thioalkyl groups, C₁-C₂₀ silicioalkylgroups, C₁-C₂₀ alkylamino groups, C₂-C₂₀ alkylimino groups, phenylgroups, phenyl groups substituted with at least one C₁-C₁₀ alkyl groupand/or with at least one C₁-C₂₀ heteroalkyl groups, thienyl groups,thienyl groups substituted with at least one C₁-C₁₀ alkyl group and/orwith at least one C₁-C₁₀ heteroalkyl groups, naphthalene, substitutednaphthalene, antracene, substituted antracene, C₄-C₂₀triciclicheteroaryl groups, and R¹ and R², are as defined in claim
 1. 4. Acompound according to the previous claim, wherein Ar is selected in thegroup consisting of the following rings (α), (β), (γ), (δ), (ε), (ζ),(η), (θ), (

):

wherein X is selected in the group consisting of S, SO, SO₂, O, Si, Se,NR¹⁷, Y is selected in the group consisting of C and N; R¹⁷ is selectedin the group consisting of hydrogen, C₂-C₂₀ linear or branched alkylgroups, C₂-C₂₀ linear or branched alkenyl groups, C₂-C₂₀ linear orbranched alkynyl groups, C₁-C₂₀ linear or branched heteroalkyl groups,C₂-C₂₀ linear or branched heteroalkenyl groups, C₂-C₂₀ linear orbranched heteroalkynyl groups, C₃-C₂₀ linear or branched cycloalkylgroups, C₂-C₂₀ linear or branched heterocycloalkyl groups, C₂-C₂₀ linearor branched alkylcarboxylic groups, C₂-C₂₀ linear or branchedalkylcarboxamide groups, C₂-C₂₀ linear or branched alkylimino groups,C₁-C₂₀ linear or branched alkylsulphonic groups, C₁-C₂₀ linear orbranched nitrile groups, C₅-C₄₀ aryl groups, C₁-C₄₀ heteroaryl groups,C₆-C₄₀ alkylaryl groups.
 5. A compound according to one of the previousclaims, wherein R¹ and/or R², independently of each other, are selectedin the group consisting of phenyl group, substituted phenyl groups,benzyl groups and substituted benzyl groups.
 6. A compound according toone of the previous claims, wherein Ar' is a unit selected in the groupconsisting of the following units (a), (b), (c), (d), (c), (f), (g),(h), (i), (l), (m), (n), (o), (p), (q), (r):

wherein A is selected in the group consisting of S, O, Se, atoms and SO,SO₂, R¹⁴—P═O, P—R¹⁴, N—R¹⁵, Si(¹⁵)₂ groups; D is selected in the groupconsisting of C, S, O Se, atoms and SO, SO₂, R¹⁴—P═O, P—R¹⁴, BR¹⁴,N—R¹⁵, Si(R¹⁵)₂ groups; B, C, independently of each other, are selectedin the group consisting of C, N atoms; E is selected in the groupconsisting of C(R¹⁵)₂, S, O, and NR¹⁵ group; R⁸, R⁹, R¹⁰, R¹¹, R¹² andR¹³, independently of each other, are selected in the group consistingof hydrogen, halogens, C₁-C₂₀ linear or branched alkyl groups, C₂-C₂₀linear or branched alkenyl groups, C₂-C₂₀ linear or branched alkynylgroups, C₁-C₂₀ linear or branched heteroalkyl groups, C₂-C₂₀ linear orbranched heteroalkenyl groups, C₂-C₂₀ linear or branched heteroalkynylgroups, C₃-C₂₀ linear or branched cycloalkyl groups, C₂-C₂₀ linear orbranched heterocycloalkyl groups, C₂-C₂₀ linear or branchedalkylcarboxylic groups, C₂-C₂₀ linear or branched alkylcarboxamidegroups, C₂-C₂₀ linear or branched alkylimino groups, C₁-C₂₀ linear orbranched alkylsulphonic groups, C₁-C₂₀ linear or branched nitrilegroups, C₅-C₄₀ aryl groups, C₆-C₄₀ alkylaryl groups; R¹⁴, R¹⁵independently of each other, are selected in the group consisting ofhydrogen, C₁-C₂₀ linear or branched alkyl groups, C₂-C₂₀ linear orbranched alkenyl groups, C₂-C₂₀ linear or branched alkynyl groups,C₁-C₂₀ linear or branched heteroalkyl groups, C₂-C₂₀ linear or branchedheteroalkenyl groups, C₂-C₂₀ linear or branched heteroalkynyl groups,C₃-C₂₀ linear or branched cycloalkyl groups, C₂-C₂₀ linear or branchedheterocycloalkyl groups, C₂-C₂₀ linear or branched alkylcarboxylicgroups, C₂-C₂₀ linear or branched alkylcarboxamide groups, C₂-C₂₀ linearor branched alkylimino groups, C₁-C₂₀ linear or branched alkylsulphonicgroups, C₂-C₂₀ linear or branched nitrile groups, C₅-C₄₀ aryl groups,C₁-C₄₀ heteroaryl groups, C₆-C₄₀ alkylaryl groups.
 7. A compoundaccording to one of claims 1 to 5, wherein the [Ar′]_(n) unit isselected in the group consisting of the following groups (s) and (t):

wherein A is as defined in claim 6; W is a moiety selected in the groupconsisting of the units (a), (b), (c), (d), (e), (f), (g), (h), (i),(l), (m), (n), (o), (p), (q), (r) of claim 6; and R¹⁶ is selected in thegroup consisting of the group consisting of hydrogen, halogens, C₁-C₂₀linear or branched alkyl groups, C₂-C₂₀ linear or branched alkenylgroups, C₂-C₂₀ linear or branched alkynyl groups, C₁-C₂₀ linear orbranched heteroalkyl groups, C₂-C₂₀ linear or branched heteroalkenylgroups, C₂-C₂₀ linear or branched heteroalkynyl groups, C₃-C₂₀ linear orbranched cycloalkyl groups, C₂-C₂₀ linear or branched heterocycloalkylgroups, C₂-C₂₀ linear or branched alkylcarboxylic groups, C₂-C₂₀ linearor branched alkylcarboxamide groups, C₂-C₂₀ linear or branchedalkylimino groups, C₁-C₂₀ linear or branched alkylsulphonic groups,C₁-C₂₀ linear or branched nitrile groups, C₅-C₄₀ aryl groups, C₁-C₄₀heteroaryl groups, C₆-C₄₀ alkylaryl groups.
 8. A compound according toany of claims 1 to 5, wherein the (Ar′)n unit is selected among thefollowing formulas (u), (v), (w), (x) and (y):

wherein n is comprised between 2 and 10 and R⁸, R⁹ are as defined inclaim
 6. 9. A compound according to claim 1, characterized in that it isselected among the following compounds 6, 8, 10, 11, 12, 13, 14, 15, 16,17, 18:


10. Use of a compound having formula selected in the group consisting offormula (I) and formula (II):

wherein: R¹, R² independently of each other, are selected in the groupconsisting of hydrogen, C₁-C₄₀ linear or branched alkyl groups, C₂-C₄₀linear or branched alkenyl groups, C₂-C₄₀ linear or branched alkynylgroups, C₁-C₄₀ linear or branched heteroalkyl groups, C₂-C₄₀ linear orbranched heteroalkenyl groups, C₂-C₄₀ linear or branched heteroalkynylgroups, C₃-C₄₀ linear or branched cycloalkyl groups, C₂-C₄₀heterocycloalkyl groups, C₂-C₄₀ linear or branched alkylcarboxylicgroups, C₂-C₄₀ linear or branched alkylcarboxamide groups, C₂-C₄₀ linearor branched alkylimino groups, C₁-C₄₀ linear or branched alkylsulphonicgroups, C₁-C₄₀ linear or branched alkyl nitrile groups; Ar, Ar′, Ar″,independently of each other, are selected in the group consisting ofmonocyclic aryl groups, substituted monocyclic aryl groups, polycyclicaryl groups, substituted polycyclic aryl groups, monocyclic heteroarylgroups, substituted monocyclic heteroaryl groups, polycyclic heteroarylgroups, substituted polycyclic heteroaryl groups and combinationsthereof as dimers, trimers and tetramers; R³ is selected in the groupconsisting of hydrogen, halogen, C₁-C₂₀ linear or branched alkyl groups,C₂-C₂₀ linear or branched alkenyl groups, C₂-C₂₀ linear or branchedalkynyl groups, C₁-C₂₀ linear or branched heteroalkyl groups, C₂-C₂₀linear or branched heteroalkenyl groups, C₂-C₂₀ linear or branchedheteroalkynyl groups, C₃-C₂₀ linear or branched cycloalkyl groups,C₂-C₂₀ heterocycloalkyl groups, C₂-C₂₀ linear or branchedalkylcarboxylic groups, C₂-C₂₀ linear or branched alkylcarboxamidegroups, C₂-C₂₀ linear or branched alkylimino groups, C₁-C₂₀ linear orbranched alkylsulphonic groups, C₁-C₂₀ linear or branched alkyl nitrilegroups; n, r, independently of each other, are integers between 1 and50; p is an integer between 0 and 5; and T is a terminal unit of thecompound and is selected among C_(i)-C₄₀ linear or branched alkylgroups, C₂-C₄₀ linear or branched alkenyl groups, C₂-C₄₀ linear orbranched alkynyl groups, C₁-C₄₀ linear or branched heteroalkyl groups,C₂-C₄₀ linear or branched heteroalkenyl groups, C₂-C₄₀ linear orbranched heteroalkynyl groups, C₃-C₄₀ linear or branched cycloalkylgroups, C₂-C₄₀ heterocycloalkyl groups, C₂-C₄₀ linear or branchedalkylcarboxylic groups, C₂-C₄₀ linear or branched alkylcarboxamidegroups, C₂-C₄₀ linear or branched alkylimino groups, C₁-C₄₀ linear orbranched alkylsulphonic groups, C₁-C₄₀ linear or branched alkyl nitritegroups, monocyclic aryl groups, substituted monocyclic aryl groups,polycyclic aryl groups, substituted polycyclic aryl groups, monocyclicheteroaryl groups, substituted monocyclic heteroaryl groups, polycyclicheteroaryl groups, substituted polycyclic heteroaryl groups, benzylgroups and substituted benzyl groups and combinations thereof as dimers,trimers and tetramers; wherein for values of p=0, T is different fromAr′, and for values of p from 1 to 5, T is different from Ar″; as anorganic semiconductor material in an electronic device.
 11. Use of acompound according to any of claims 2 to 9 as an organic semiconductormaterial in an electronic device.
 12. Use according to claim 10 or 11,as n-type organic semiconductor material in an electronic device.
 13. Anelectronic device comprising a semiconductor layer in contact with anumber of electrodes, wherein the semiconductor layer includes at leastone compound having formula selected in the group consisting of formula(I) and formula (II):

wherein: R¹, R² independently of each other, are selected in the groupconsisting of hydrogen, C₁-C₄₀ linear or branched alkyl groups, C₂-C₄₀linear or branched alkenyl groups, C₂-C₄₀ linear or branched alkynylgroups, C₁-C₄₀ linear or branched heteroalkyl groups, C₂-C₄₀ linear orbranched heteroalkenyl groups, C₂-C₄₀ linear or branched heteroalkynylgroups, C₃-C₄₀ linear or branched cycloalkyl groups, C₂-C₄₀heterocycloalkyl groups, C₂-C₄₀ linear or branched alkylcarboxylicgroups, C₂-C₄₀ linear or branched alkylcarboxamide groups, C₂-C₄₀ linearor branched alkylimino groups, C₁-C₄₀ linear or branched alkylsulphonicgroups, C₁-C₄₀ linear or branched alkyl nitrile groups; Ar, Ar′, Ar″,independently of each other, are selected in the group consisting ofmonocyclic aryl groups, substituted monocyclic aryl groups, polycyclicaryl groups, substituted polycyclic aryl groups, monocyclic heteroarylgroups, substituted monocyclic heteroaryl groups, polycyclic heteroarylgroups, substituted polycyclic heteroaryl groups and combinationsthereof as dimers, trimers and tetramers; R³ is selected in the groupconsisting of hydrogen, halogen, C₁-C₂₀ linear or branched alkyl groups,C₂-C₂₀ linear or branched alkenyl groups, C₂-C₂₀ linear or branchedalkynyl groups, C₁-C₂₀ linear or branched heteroalkyl groups, C₂-C₂₀linear or branched heteroalkenyl groups, C₂-C₂₀ linear or branchedheteroalkynyl groups, C₃-C₂₀ linear or branched cycloalkyl groups,C₂-C₂₀ heterocycloalkyl groups, C₂-C₂₀ linear or branchedalkylcarboxylic groups, C₂-C₂₀ linear or branched alkylcarboxamidegroups, C₂-C₂₀ linear or branched alkylimino groups, C₁-C₂₀ linear orbranched alkylsulphonic groups, C₁-C₂₀ linear or branched alkyl nitrilegroups; n, r, independently of each other, are integers between 1 and50; p is an integer between 0 and 5; and T is a terminal unit of thecompound and is selected among C₁-C₄₀ linear or branched alkyl groups,C₂-C₄₀ linear or branched alkenyl groups, C₂-C₄₀ linear or branchedalkynyl groups, C₁-C₄₀ linear or branched heteroalkyl groups, C₂-C₄₀linear or branched heteroalkenyl groups, C₂-C₄₀ linear or branchedheteroalkynyl groups, C₃-C₄₀ linear or branched cycloalkyl groups,C₂-C₄₀ heterocycloalkyl groups, C₂-C₄₀ linear or branchedalkylcarboxylic groups, C₂-C₄₀ linear or branched alkylcarboxamidegroups, C₂-C₄₀ linear or branched alkylimino groups, C₁-C₄₀ linear orbranched alkylsulphonic groups, C₁-C₄₀ linear or branched alkyl nitrilegroups, monocyclic aryl groups, substituted monocyclic aryl groups,polycyclic aryl groups, substituted polycyclic aryl groups, monocyclicheteroaryl groups, substituted monocyclic heteroaryl groups, polycyclicheteroaryl groups, substituted polycyclic heteroaryl groups, benzylgroups and substituted benzyl groups and combinations thereof as dimers,trimers and tetramers; wherein for values of p=0, T is different fromAr′, and for values of p from 1 to 5, T is different from Ar″.
 14. Anelectronic device comprising a semiconductor layer in contact with anumber of electrodes, wherein the semiconductor layer includes at leastone compound according to one of claims 2 to 10.